Poland's ruling Civic Platform (PO) party has secured the highest number of provincial assembly seats in the Nov. 16 vote, the state election commission said, a surprising result seen as likely to further aggravate tensions over the already contentious vote.

The official results, published after a vote count dogged by a glitch in a new computer system, also showed that the central and eastern European country's largest opposition party, Law and Justice (PiS), received the highest share of votes at 26.85 percent, coming ahead of PO with 26.36 percent of the vote.

The results of the elections defied an exit poll that showed PiS ahead of PO by a 4-percentage-point margin, which would have given the party its first nationwide victory in nine years.

The center-right PO won 179 seats in provincial assemblies, the state election commission PKW said Saturday. The conservative bloc led by PiS came second, securing 169 seats.

The junior ruling coalition partner, PSL, traditionally popular in rural areas, won 159 seats, or 23.68 percent of the vote, while the leftist SLD party secured 28 seats with 8.78 percent.

The commission said 17.9 percent of the total number of votes to provincial assemblies were invalid.

The delay in publishing the results, caused by the failure of a piece of software intended to aid the vote count, led the election committee head to say he would resign.

Earlier last week, PiS called for a rerun of the elections, while President Bronislaw Komorowski dismissed the suggestion as the height of insanity.

Regional elections are held every four years to choose mayors, provincial assembly members and other local authorities. In 2010, PO won 30.9 percent of the votes, followed by PiS on 23.1 percent and the PSL party with 16.3 percent.